Flink 动态读取Nacos配置

1.需求：实时读取Nacos的配置，打印在控制台
2.额外的依赖：

    
      com.alibaba.nacos
      nacos-client
      1.4.2
    

3. 代码
   很简单,就直接贴了

package com.xianghu.flink.nacos;

import com.alibaba.nacos.api.NacosFactory;
import com.alibaba.nacos.api.config.ConfigService;
import com.alibaba.nacos.api.config.listener.Listener;
import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.SourceFunction;

import java.util.Map;
import java.util.Properties;
import java.util.UUID;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;

public class ReadConfigFromNacos {

  public static void main(String[] args) throws Exception {
    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
    env.setParallelism(1);

    // 读取nacos配置 --serverAddr http://localhost:8848 --dataId flink-nacos --group DEFAULT_GROUP
    ParameterTool parameter = ParameterTool.fromArgs(args);
    env.getConfig().setGlobalJobParameters(parameter);

    env.addSource(new SourceFunction<String>() {
      boolean flag = true;

      @Override
      public void run(SourceContext<String> sourceContext) throws Exception {
        while (flag) {
          // 向下游发送数据，触发计算
          sourceContext.collect(UUID.randomUUID().toString());
          TimeUnit.SECONDS.sleep(2);
        }
      }

      @Override
      public void cancel() {
        flag = false;
      }
    }, TypeInformation.of(String.class))

        .map(new RichMapFunction<String, String>() {
          private String nacosValue;

          @Override
          public String map(String s) throws Exception {
            // 直接返回从nacos读到的值
            return nacosValue;
          }

          @Override
          public void open(Configuration parameters) throws Exception {
            // 获取nacos配置
            Map<String, String> nacosConf = getRuntimeContext()
                .getExecutionConfig()
                .getGlobalJobParameters()
                .toMap();

            String serverAddr = nacosConf.get("serverAddr");
            String dataId = nacosConf.get("dataId");
            String group = nacosConf.get("group");

            Properties properties = new Properties();
            properties.put("serverAddr", serverAddr);

            ConfigService configService = NacosFactory.createConfigService(properties);
            // context是key=value模式，多个值换行符分割，这里取第一行的key-value对
            String content = configService.getConfig(dataId, group, 5000);
            // 初始化 nacosValue
            nacosValue = content.split("\n")[0].split("=")[1];

            // 添加Listener，监控数据变化
            configService.addListener(dataId, group, new Listener() {
              @Override
              public void receiveConfigInfo(String configInfo) {
                // 有变更时，更新nacosValue
                nacosValue = configInfo.split("\n")[0].split("=")[1];
              }

              @Override
              public Executor getExecutor() {
                return null;
              }
            });
          }
        }).print();

    env.execute();
  }
}

4.现在的nacos配置

5.运行程序，打印当前配置

6.flink不停机，修改nacos配置，发布

可以看到，新的value已经打印到控制台。很简单，只是利用监听功能，Apollo的动态配置读取，也可以使用类似的操作实现。